High Throughput Tau Oligomer Assay for Drug Screening for Alzheimer's Disease Project Summary: There is a large and rapidly growing unmet need for disease modifying drugs for Alzheimer's disease. Currently there are 18 million cases of AD worldwide;by 2025 this number is expected to increase to 34 million. Presently, only 5 mildly effective AD symptom-treating drugs exist, but none that treat the underlying neurodegenerative processes. Tau is becoming a more prominent target for the development of disease- modifying drugs (DMDs), as its role in neurodegeneration is becoming better understood. Mutations in the gene for tau protein MAPT are causative of dementia and tau pathology correlates well with AD progression. At the same time, late stage clinical failures for therapeutics based on the amyloid hypothesis have raised questions on solely targeting A2. Strong evidence has emerged implicating tau oligomers as playing a direct role in disease pathogenesis for AD and over 20 other neurodegenerative diseases (Brunden et al. 2008;Davidowitz et al. 2008). To discover drugs targeting tau oligomerization methods were developed to select compounds inhibiting tau self-interaction, and an assay using AlphaScreen detection technology was selected for further development for high throughput screening (Chatterjee et al. 2008). In addition, the phage display- atomic force microscopy method developed by Dr. Sierks (ASU) was used to isolate antibody fragments (scFvs) specifically binding to tau oligomers that will be adopted in the cell based screening assays. The specific aims of the proposed program are as follows: " Convert the tau oligomer assay to HTS format " Transfer Assay to the Michigan High Throughput Screening Center (MHTSC) for automation and screening of a highly optimized compound library (100,000 compounds) and carry out medicinal chemistry analysis to model the pharmacophore and select additional chemotypes for screening " Select compounds using tau oligomer specific antibody fragments in cell based assays The anticipated outcome of the proposed Phase II program is the selection of at least three or more lead candidate compounds targeting tau oligomers that will be developed during the Phase III program and evaluated in animal models of AD and tauopathies. To attain this result, the high throughput assay will be optimized and transferred to the Michigan High Throughput Screening Center where their Select Set library of approximately 100,000 compounds will be screened under the direction Dr. Robert Kilkuskie Hits will be validated and a structural pharmacaophore model will be developed. Toxic compounds will be eliminated using a neurocytotoxicity assay. Three or more scFvs will be selected with high sensitivity and specificity that will be used to identify compounds inhibiting tau self-association using in vitro cell based assays. Antibody fragments, in addition to enabling the primary goal, are supportive of the company's other programs including its tau biomarker development program and its tau immunotherapeutic program. However, the primary goal of the program is to advance the tau oligomer drug discovery platform to identify active inhibitors as lead candidates for IND enabling studies. Key Words Alzheimer's disease, tauopathy, neurodegenerative disease, drug discovery, tau oligomer, phage display, antibody fragment, scFv, high throughput screening PUBLIC HEALTH RELEVANCE: The proposed program focuses on developing a high throughput screening assay targeting tau oligomers for drug discovery for Alzheimer's disease (AD). This project was inspired by observations that accumulation of tau oligomers has been shown to correlate well with neuronal loss and memory impairment in AD and in tauopathy mouse models. OLIGOMERIX has developed in vitro assays for screening compounds that inhibit the formation of cytotoxic tau oligomers. This program aims to 1.) .Convert the tau oligomer assay to HTS format;2.) Transfer Assay to the Michigan High Throughput Screening Center (MHTSC) for automation and screening of a highly optimized compound library (100,000 compounds) and carry out medicinal chemistry analysis to model the pharmacophore;3.) Select compounds using tau oligomer specific antibody fragments and cell based screening to identify lead candidates for future animal studies and pre-clinical development.